In booster steering devices of the kind described herein it has heretofore been known to rigidly connect a torque rod to the rotary valve plug of a rotary valve which valve plug is encompassed by a valve sleeve connected to the opposite end of the torque rod. Such devices are known in various patents such as U.S. Pat. No. 4,200,030 and German OS No. 23 45 384 wherein the U.S. patent discloses a ball-nut arrangement and the German publication discloses a rack type arrangement, both incorporated herein by reference.
The valve components have coacting grooves and upon relative roation of the components, one chamber of a servomotor is pressurized while the other is exhausted. A piston of the servomotor connects to the steering mechanism for operating the vehicle wheels.
The return of the vehicle wheels for straight ahead driving is generally accomplished by suitable axial geometry in various ways, but in order to provide return force, restoring energy is stored in the axial geometry during a steering operation. Thus the return force must be initially overcome during a steering movement and this requires considerable addition of steering energy.